KR20200068527A - Oxidation fiber manufacturing method - Google Patents

Abstract

The present disclosure mainly uses a transmitting unit to drive a fiber yarn bunch to pass an operation region of a microwave processing unit, and the microwave is focused to perform an ultra-fast pre-oxidization process on the passed fiber yarn bunch, thereby processing the fiber yarn bunch to form an oxidation fiber yarn bunch. Not only an oxidization time of an oxidation fiber can be reduced, but also a cross section area of the oxidation layer of the oxidation fiber in the oxidation fiber yarn bunch generated by the microwave focusing oxidization process occupies more than 50 % of the cross section area of the oxidation fiber in the oxidation fiber yarn bunch. Thus, a shell-core structure of the oxidation fiber can be efficiently reduced. Even, the oxidation fiber has no obvious shell-core structure. Accordingly, relatively positive and reliable means for increasing the performance of a carbon fiber can be provided.

Description

Oxidation fiber manufacturing method{OXIDATION FIBER MANUFACTURING METHOD}

The present invention relates to a carbon fiber pre-oxidation technique, and specifically discloses a method for producing oxidized fibers that helps to improve the performance of carbon fibers.

Carbon fiber is a new carbon material with a carbon concentration of 90%, and organic fiber is transformed into carbon fiber through a sequential heat treatment process. Carbon fiber has the advantages of high specific strength, high specific modulus, high conductivity and thermal conductivity, low thermal expansion coefficient, low density, high temperature resistance, fatigue resistance, creep resistance and self-lubrication, aerospace, civilian It is an ideal functional and structural material widely used in aviation and transportation and other fields, and has a wide range of applications.

The carbon fiber manufacturing process using polyacrylonitrile (PAN) as raw silk includes polymerization, spinning, pre-oxidation and carbonization processes, and the pre-oxidation process is a core structural modification step of the carbon fiber manufacturing process. It is a time-consuming step in the heat treatment process aimed at transforming a linear polymer chain into an oxidized fiber having a heat-resistant structure. In the next carbonization process, the oxidized fiber does not burn and does not melt, and the fiber shape can be maintained.

Structural modification of raw silk in the pre-oxidation process mainly determines the structure and performance of the carbon fiber. During industrial production, a preliminary oxidation process using a gradient temperature increase method is mainly used, and an appropriate gradient temperature range is required in the process. If the initial temperature is too low, it does not contribute to the pre-oxidation process and increases the consumption time, which is expensive. In contrast, if the initial temperature is too high, the heat release of the severe reaction allows the macromolecular chain of polyacrylonitrile to melt, and the macromolecular chain of polyacrylonitrile does not have heat resistance. In addition, if the end temperature is too high, concentrated heat release destroys the structure of the pre-oxidized silk, and it is difficult to produce high-strength carbon fibers by oxidizing the pre-oxidized silk. However, if the end temperature is too low, the raw sand is not sufficiently pre-oxidized.

In addition, when the pre-oxidation process is performed by heating, as the pre-oxidation proceeds, since heat is transferred from the outer layer of the raw sand to the inner layer of the raw sand, the outer layer of the raw sand first has an oxide layer having a compact trapezoidal structure ( That is, the shell portion), which prevents the diffusion of oxygen to the core portion of the raw sand. As such, as shown in FIG. 1, this is a distinct difference between the oxide layer 111 (shell portion) produced by oxidizing one fiber 11 in the oxidized fiber 10 and the unoxidized core portion 112. This results in a shell core structure, and there is a shell-core interface 113 between the oxide layer 111 and the core portion 112. To examine the shell-core structure, a scanning electron microscope (SEM) takes a substantial image to observe the cross-section of the oxide fiber and calculates the cross-sectional area of the oxide layer, core portion and oxide fiber. The grade (%) of the core portion can be used to evaluate the grade of the shell-core structure, where the grade of the core portion is the value of the sum of the cross-sectional area divider oxide layer of the core portion and the cross-sectional area of the core portion, i.e. cross-sectional area divider oxidation of the core portion It is the value of the cross-sectional area of the fiber. In addition, physical properties of the oxidized fiber 10 and the carbon fiber produced therefrom, such as tensile strength and tensile modulus, are further determined by the degree of oxidation and cyclization of the oxidized fiber 10 or the oxide layer 111. The higher the degree of oxidation and cyclization of the oxide fiber 10 or the oxide layer 111, the higher the tensile strength and tensile modulus of the carbon fiber produced by the oxide fiber 10. The oxide layer 111 exhibits an oxidized state and its structure is compact, so that the manufactured carbon fiber has high tensile strength and high tensile modulus. The core portion 112 exhibits a non-completely oxidized state or a non-oxidized state, and the structure is loosened, so that the produced carbon fiber has low tensile strength and low tensile modulus. Since the oxidation degree of the oxide layer 111 and the core portion 112 are different, the obtained shell-core structure is one important factor that degrades the tensile strength of the carbon fiber. Therefore, a method of shortening the pre-oxidation time in the pre-oxidation reaction process and a method of simultaneously increasing the pre-oxidation degree and removing the shell core structure reduce carbon fiber production cost and increase performance (such as tensile strength and tensile modulus). It has importance in ordering.

Accordingly, an object of the present invention is to provide a method for producing an oxidized fiber which shortens the oxidation time of the oxidized fiber, efficiently removes the shell-core structure of the oxidized fiber, and moreover produces an oxidized fiber having no apparent shell-core structure. will be.

The present invention provides a method for producing an oxidized fiber that is used to pre-oxidize a fiber yarn bunch to form a bundle of oxidized fiber yarns. A bundle of fiber yarns is formed by only one fiber, or a bundle of fiber yarns is formed by joining a plurality of fibers. The bundle of oxide fiber yarns is formed by only one oxide fiber, or the bundle of oxide fiber yarns is formed by combining a plurality of oxide fibers. The method of making an oxide fiber includes the following steps:

Providing a bundle of yarns; Prepare a bundle of the fiber yarns; And

Microwave treatment step: The fiber yarn bundle is exposed to microwave treatment conditions to form a bundle of oxidized fiber yarn.

In one embodiment, the method of making an oxidized fiber of the present invention is used to pre-oxidize a bundle of fiber yarns to form a bundle of oxidized fiber yarns. A bundle of fiber yarns is formed by only one fiber, or a bundle of fiber yarns is formed by joining a plurality of fibers. The bundle of oxide fiber yarns is formed by only one oxide fiber, or the bundle of oxide fiber yarns is formed by combining a plurality of oxide fibers. The method of making oxidized fiber includes the following steps:

a. Providing a transmission unit and a microwave processing unit;

b. Providing a bundle of fiber yarns, placing a bundle of fiber yarns in the transmission unit, and moving the bundle of fibers to pass through the microwave processing unit;

c. Activating the microwave processing unit to generate microwave processing conditions by the microwave processing unit;

d. Activating the transfer unit to move the fiber yarn bundle to be processed for a treatment time under the microwave treatment condition by the transfer unit, such that the fiber yarn bundle forms the oxide fiber yarn bundle.

According to the method for producing an oxidized fiber, the fiber of the fiber yarn bundle is pre-oxidized using the method for producing an oxidized fiber to form an oxidized fiber.

According to the method of manufacturing the oxidized fiber, the microwave processing conditions include a microwave frequency of 300 MHz to 300,000 MHz; Microwave power of 1 kW/m ² to 1000 kW/m ² ; The operating temperature is 100°C to 600°C; And a gas atmosphere that is at least one of oxygen, air, and ozone.

According to the method for producing an oxide fiber, the treatment time is 1 minute to 40 minutes.

According to the method for producing an oxidized fiber, microwave power is 10 kW/m 2 to 24 kW/m 2.

According to the oxide fiber manufacturing method, the microwave frequency is 2000 MHz to 3000 MHz, the operating temperature is 150°C to 350°C, and the treatment time is 5 minutes to 20 minutes.

According to the oxidized fiber manufacturing method, the fiber yarn bundle is one of polyacrylonitrile (PAN) fiber, pitch fiber, and another organic fiber.

According to the method of manufacturing the oxidized fiber, the transfer unit is provided with a supply unit for providing the fiber yarn bundle, a winding unit for continuously pulling and transmitting the fiber yarn bundle, and an oven body through which the fiber yarn bundle passes. In the microwave processing unit, a magnetron for generating microwave frequency and microwave power is installed in the oven body, and a gas supply unit for injecting a gas atmosphere into the oven body.

According to the method of manufacturing an oxide fiber, the winding unit, the magnetron and the gas supply unit are electrically connected to the control unit.

According to the method of manufacturing the oxide fiber, a thermos unit is installed inside the oven body.

According to the method for producing an oxidized fiber, the insulating unit is at least one of metal oxide, carbide and high microwave sensitive material.

According to the method for producing oxidized fibers, the batches of disposed fiber yarns are placed in the oven body in a repeating and winding manner, and are continuously irradiated by the microwave processing unit.

In the method of manufacturing an oxidized fiber of the present invention, an ultra-high-speed pre-oxidation process is applied to a bundle of fiber yarns by mainly concentrating microwaves using a microwave processing unit to form a oxidized fiber by processing a bundle of fiber yarns. In addition to shortening the oxidation time of the oxidized fiber, the cross-sectional area of the oxide layer in the oxidized fiber occupies 50% or more of the sectional area of the oxidized fiber, so that the shell-core structure can be efficiently removed. If the cross-sectional area of the oxide layer in the oxide fiber occupies 80% or more of the cross-sectional area of the oxide fiber, even the oxide fiber does not have an apparent shell-core structure. Thus, a relatively positive and reliable means is provided to improve the performance of the carbon fiber.

The accompanying drawings are included to provide a detailed description of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate exemplary embodiments of the invention and together with the description, serve to explain the principles of the invention.
1 is a schematic view showing a shell-core structure of a conventional oxide fiber.
2 is a basic flow chart showing a method for producing an oxidized fiber of the present invention.
3 is a schematic diagram showing the configuration of a transmission unit and a microwave processing unit according to the method for producing an oxide fiber of the present invention.
FIG. 4 is an oxidation curve of oxidized fibers associated with a bundle of fiber yarns in which a microwave focusing process of 12 kW/m 2, 16 kW/m 2, 20 kW/m 2, and 24 kW/m 2 was performed and a conventional heating process, respectively.
FIG. 5 is a cyclization curve diagram of oxidized fibers associated with a bundle of fiber yarns in which a 24 mm 2 /m 2 microwave focusing process is performed for 2 minutes, 4 minutes, 5 minutes, 10 minutes and 15 minutes, respectively.
FIG. 6 is a substantial cross-sectional image of oxidized fibers of a bundle of fiber yarns in which a 24 kW/m 2 microwave focusing process was performed for 5 minutes.
FIG. 7 is a substantial cross-sectional image of the oxidized fiber of a bundle of fiber yarns in which a 24 mm2/m2 microwave focusing process was performed for 10 minutes.
FIG. 8 is a substantial cross-sectional image of the oxidized fiber of a bundle of fiber yarns in which a 24 mm2/m2 microwave focusing process was performed for 15 minutes.
9 is a flowchart of another method of manufacturing an oxidized fiber of the present invention.
10 is a schematic view showing the structure of an oven body related to the method for producing an oxidized fiber of the present invention.
11 is a schematic view showing the structure of the oxidized fiber of the present invention.

The present invention mainly provides a method for producing an oxidized fiber which shortens the oxidation time of the oxidized fiber, effectively removes the shell-core structure of the oxidized fiber, and does not have an apparent shell-core structure in the oxidized fiber. 2 and 3, the method for manufacturing an oxidized fiber basically includes the following steps.

Step A: The transmission unit 30 and the microwave processing unit 40 are provided. When the present invention is implemented, the transmission unit 30 includes a supply unit 31 for providing a fiber yarn bundle 20, a winding unit 32 for continuously pulling and transmitting the fiber yarn bundle 20 continuously, And an oven body 33 through which the fiber yarn bundle 20 passes is installed, the fiber yarn bundle 20 is simply formed by one fiber (not shown), or alternatively, the fiber yarn bundle 20 is It is formed by combining a plurality of fibers. In the microwave processing unit 40, a magnetron 41 is installed in the oven body 33 for generating microwaves, and a gas supply unit 42 for injecting a gas atmosphere into the oven body 33 is also installed. The gas supply unit 42 is connected to the gas inlet 331 of the oven body 33, and the gas containing oxygen is injected into the oven body 33 through the gas inlet 331, so that the It is discharged from the oven body 33 through the gas outlet 332. Inside the oven body 33, a warming unit 34 is mounted. Preferably, the microwave processing unit 40 is provided with a plurality of magnetrons 41 in the oven body 33. The magnetron 41 is disposed on the top and bottom surfaces of the oven body 33, and the magnetrons 41 disposed on the top and bottom surfaces of the oven body 33 are disposed in a mutually or offset manner, or a magnetron ( 41) is arranged on a single side (such as the upper or lower side) of the oven body 33. 3, the magnetron 41 is disposed on the upper and lower sides of the oven body 33, and the magnetron 41 disposed on the upper and lower sides of the oven body 33 is disposed to correspond to each other. . Optionally, the magnetrons 41 disposed on the upper and lower sides of the oven body 33 are disposed to correspond to each other as shown in FIG. 3, so that the bundle of fiber yarns 20 passing through the oven body 33 By simultaneously and uniformly irradiating microwaves on the upper and lower portions, the length of the oven body 33 can be correspondingly shortened, so that the processing time can be shortened, thereby increasing the production speed.

Step B: Providing a bundle of fiber yarns 20, placing a bundle of fiber yarns 20 in the transmission unit 30, and transferring the fiber yarn bundles 20 to move the microwave yarn processing unit 40 Pass through. For example, the wound yarn bundle 20 is wound in a manner such that the wound yarn bundle 20 can be continuously moved by the transmission unit 30 to pass through the operating region of the microwave processing unit 40. 30). In an embodiment, the wound fiber yarn bundle 20 is disposed in the supply unit 31, the distal end of the fiber yarn bundle 20 passes through the oven body 33 and is fixed to the winding unit 32, the The fiber yarn bundle 20 may be one of polyacrylonitrile (PAN) fiber, pitch fiber, and another organic fiber.

Step C: Activate the microwave processing unit 40 and use the microwave processing unit 40 to generate microwave processing conditions. The microwave processing conditions include a microwave frequency of 300 MHz to 300,000 MHz; Microwave power of 1 kW/m ² to 1000 kW/m ² ; The operating temperature is 100°C to 600°C; And a gas atmosphere that is at least one of oxygen, air, and ozone. The gas atmosphere is the gas with oxygen. In this embodiment, the gas supply unit 42 is used to inject gas into the interior of the oven body 33.

Step D: Operating the transmission unit 30 to move the fiber yarn bundle 20 to be exposed to microwave treatment conditions during the treatment time, thereby transforming the fiber yarn bundle 20 into an oxidized fiber yarn bundle 20A. For example, the bundle of fiber yarns 20 is moved by the transmission unit 30 to pass through the operating area of the microwave processing unit 40 at a rate at which the microwave focusing process is continuously applied for 1 to 40 minutes, i.e. The treatment time is 1 minute to 40 minutes. In this embodiment, the fiber yarn bundle 20 is moved by the transfer unit 30 to pass through the oven body 33, so that the microwave focusing process is continuously applied for 1 to 40 minutes, and the oxide fiber yarn bundle 20A ). In addition, the fiber yarn bundle 20 in the oven body 33 is wound and also passes through the oven body 33 repeatedly at a rate at which the microwave focusing process is continuously applied for 1 minute to 40 minutes to bundle the oxidized fiber yarn bundle 20A ) To form a bundle of oxide fiber yarns 20A. For example, a bundle of fiber yarns 20 at the distal end of the oven body 33 enters the interior of the oven body 33 and is transmitted to the rear end of the oven body 33. Next, the fiber yarn bundle 20 is transferred from the rear end of the oven body 33 to the front end of the oven body 33, and then transferred from the front end of the oven body 33 to the rear end of the oven body 33 again. . This method repeatedly wraps the fiber yarn bundle 20 until the requirements are met, and then sends the fiber yarn bundle 20 from the rear end of the oven body 33 to form the oxidized fiber yarn bundle 20A. The required length of the oven body 33 can be sufficiently reduced by the repeated winding method used above.

Therefore, using the method of manufacturing an oxidized fiber, under the operation of the transmission unit 30, the fiber yarn bundle 20 is moved to pass through the operating region of the microwave processing unit 40 at a predetermined speed. During the course of the fiber yarn bundle 20 passing through the operating region of the microwave processing unit 40, the microwave focus is continuously used to apply an ultra-fast pre-oxidation process to the fiber yarn bundle 20, thereby making the fiber yarn bundle ( 20) is processed to form a bundle of oxide fiber yarns 20A. As shown in Fig. 4, the fiber yarn bundle 20 is formed by only one fiber, or the fiber yarn bundle 20 is formed by joining a plurality of fibers; The bundle of oxide fiber yarns 20A is formed of only one oxide fiber, or the bundle of oxide fiber yarns 20A is formed by bonding a plurality of oxide fibers. The method for producing an oxidized fiber of the present invention may be used to pre-oxidize the fibers of the fiber yarn bundle 20 to form the oxidized fiber 21.

As shown in Fig. 4, the fiber yarn bundle 20 is applied to a non-microwave process and a microwave focusing process of microwave power of 12 kW/m 2, 16 kW/m 2, 20 kW/m 2 and 24 kW/m 2, respectively. It is possible to obtain a result that the oxidation degree of the oxidized fiber 21 in the oxidized fiber yarn bundle 20A is 100% by applying a microwave focusing treatment of 24 kW/m 2 to the fiber yarn bundle 20 for 10 minutes. Corresponding to the fiber yarn bundle 20, the oxide fiber yarn bundle 20A is formed by only one oxide fiber, or the oxide fiber yarn bundle 20A is formed by combining a plurality of oxide fibers. Similarly, a microwave focusing treatment of 20 mm 2 /m 2 is performed for 15 minutes on the fiber yarn bundle 20, so that the degree of oxidation of the oxidized fiber 21 in the bundle 20A of oxides reaches 100%. The fiber bundle bundle 20 is subjected to a microwave focusing treatment of 16 kW/m 2 for 25 minutes, so that the oxidation degree of the oxidized fiber 21 of the oxidized fiber bundle 20A reaches 100%. However, even if 12 ㎾/m 2 microwave focusing treatment is applied to the fiber yarn bundle 20 for 40 minutes, the oxidation degree of the oxidized fiber 21 in the oxidized fiber yarn bundle 20A still cannot reach 100%, 89 % Can be reached. When a conventional heating process is applied at 270°C without microwaves to heat the fiber yarn bundle 20 for 40 minutes, the oxidation degree of the oxidized fiber 21 can only reach 70%. Therefore, when the microwave process provided by the present invention is compared with a conventional heating process, the present invention can effectively increase the degree of oxidation of the oxidized fiber 21 and shorten the process time. In particular, when a microwave focusing treatment of 24 kW/m 2 is applied to the fiber yarn bundle 20 for 10 minutes, the oxidation degree of the oxidized fiber 21 of the oxidized fiber yarn bundle 20A can reach 100%, 24 kW/m 2 And 40 minutes is the best treatment condition for the oxidation step.

As shown in FIG. 5, microwave focusing treatment of 24 kW/m 2 for 2 minutes, 4 minutes, 5 minutes, 10 minutes, and 15 minutes, respectively, was performed to check the degree of cyclization of the formed oxidized fibers 21. 20). The degree of cyclization of the oxide fiber 21 reaches 100% after 5 minutes have elapsed. Therefore, the required time of 5 minutes for the degree of cyclization to reach 100% is less than the required time of 10 minutes for the degree of oxidation to reach 100%. Referring to FIGS. 6, 7 and 8 at the same time, the cross-section of the oxidized fiber 21 associated with the bundle of oxidized fiber yarns 20A treated with a microwave focusing treatment of 24 kW/m 2 for 5 minutes, 10 minutes, and 15 minutes It is imaged with a scanning electron microscope, and a substantial cross-sectional image can be obtained. The oxide layer 211 occupies 99.0% or more of the oxidized fiber 21, or the sectional area of the oxide layer 211 occupies 99.0% or more of the sectional area of the oxidized fiber 21, and there is no apparent shell-core structure.

See Table 1 and Table 2 at the same time. Table 1 is a comparative table showing the measured tensile strength of fiber yarn bundles 20, oxidized fiber yarn bundles 20A, and carbon fiber yarn bundles formed by the next carbonization, two sets of fiber yarn bundles 20, oxidized fibers The yarn bundle 20A and the carbon fiber yarn bundle are each treated by a conventional heat pipe heating process and a microwave process of the method for producing an oxidized fiber of the present invention. Table 2 is a comparison table showing measured tensile modulus of the fiber yarn bundle 20, the oxidized fiber yarn bundle 20A, and the carbon fiber yarn bundle formed by the following carbonization, two sets of fiber yarn bundle 20, oxidation The fiber yarn bundles 20A and carbon fiber yarn bundles are each treated by a conventional heat pipe heating process and the microwave process of the method for producing an oxidized fiber of the present invention. In the conventional heat transfer tube heating process, the treatment conditions are oven body temperature 270° C., treatment time 40 minutes, and the result of the obtained physical properties is referred to as “Comparative Example 1”. In the microwave process of the method for producing an oxidized fiber of the present invention, the treatment conditions are an oven body temperature of 220° C., a microwave frequency of 2450 MHz, a microwave power of 24 kW/m 2 and a treatment time of 10 minutes, and the resulting physical properties are referred to as “Example 1”. . In both Comparative Example 1 and Example 1, the fiber yarn bundle 20 is made of polyacrylonitrile.

Tensile strength (MPa) Fiber yarn bundle Bundle of oxide fiber yarn Carbon fiber yarn bundle Comparative Example 1 865 221 2824 Example 1 865 164 3675

In Table 1, Example 1 shows that the tensile strength of the final carbon fiber yarn carbonized by the bundle of oxidized fiber yarns treated by the microwave process of the method for producing an oxidized fiber of the present invention is 1.3 times that of Comparative Example 1 (i.e., 3675 Division 2824), the tensile strength was improved by 30%. The microwave process can more fully oxidize polyacrylonitrile, and the tensile strength of the oxidized fiber yarn bundle associated with the microwave process is slightly less than the tensile strength of the oxidized fiber yarn bundle associated with the conventional electric thermal management heating process. The microwave process of the method of making an oxidized fiber of the present invention is another proof that the degree of oxidation of the fiber yarn bundle can be further increased.

Tensile modulus (GPa) Fiber yarn bundle Bundle of oxide fiber yarn Carbon fiber yarn bundle Conventional example 8.82 6.03 194.4 Example 8.82 6.92 227.1

In Table 2, Example 1 shows that the tensile modulus of the final carbon fiber yarn bundle carbonized by the bundle of oxidized fiber yarns treated by the microwave process of the method for producing an oxidized fiber of the present invention is 1.17 times that of Comparative Example 1 (i.e., 227.1 Divide 194.4), the tensile modulus was improved by 17%.

Therefore, compared to the bundle of oxidized fiber yarns each produced by a bundle of fiber yarns in which the conventional heating process and the microwave process of the present invention were performed, the microwave method of the present invention reduces the time required by the conventional heating process to 40 minutes. The process efficiency was improved by 3 times, and the process time was shortened. Compared to conventional heating processes, the present invention can improve the 30% tensile strength and 17% tensile modulus of carbon fiber yarn bundles. The present invention occupies at least 99.0% of the cross-sectional area of the oxidized layer 2111 of the oxidized fiber 21 of the oxidized fiber yarn bundle 20A, compared to a conventional heating process, and the apparent shell- There is no core structure. The cross section of the oxidized fiber yarn bundle 20A is more uniform, so the tensile strength and tensile modulus of the carbon fiber yarn bundle are increased. Thus, a relatively positive and reliable means for improving carbon fiber performance is provided.

In the case of carrying out the method for producing an oxidized fiber of the present invention, a fiber bundle is processed by applying a microwave focusing process of preferably 5 minutes to 10 minutes, preferably 24 kW/m 2. Of course, when implementing the method for producing an oxidized fiber of the present invention, a 24 kW/m 2 microwave focusing process is applied to process a bundle of fiber yarns for 5 minutes to 10 minutes. As shown in Fig. 3, the transfer unit 30 is provided with a supply unit 31, a winding unit 32 and an oven body 33, and the supply unit 31 provides a bundle of fiber yarns 2 Used, the fiber yarn bundle 20 can pass through the oven body 33, the winding unit 32 drags the fiber yarn bundle 20 for continuous transmission and accommodates the oxidized fiber yarn bundle 20A It is used to. In addition, a magnetron 41 and a gas supply unit 42 are installed in the microwave processing unit 40, a magnetron 41 is disposed in the oven body 33 to generate microwaves, and the gas supply unit 42 is It is used to inject gas with oxygen into the oven body 33. Therefore, in the method for producing an oxidized fiber of the present invention, the continuous carbon fiber yarn bundle production method in which the fiber yarn bundle 20 passes through the oven body 33 without receiving and winding the winding unit 32, and then carbonization is performed Alternatively, or alternatively, the method for producing an oxidized fiber of the present invention is applied to a production method in which a bundle of fiber yarns 20 that are wound is unwound by the supply unit 31 and received and wound up by the winding unit 32.

Of course, the method for producing an oxidized fiber of the present invention can also be applied to a batch generation method. The embodiment of the batch generation method may sequentially execute the following steps as shown in FIG. 9. The method for manufacturing an oxidized fiber of the present invention can be applied to pre-oxidize a fiber yarn bundle 20 to form an oxidized fiber yarn bundle 20A. The steps of Figure 9 are described as follows.

Yarn bundle providing step (S01): prepares a fiber yarn bundle (20). The fiber yarn bundle 20 is formed of only one fiber, or alternatively, is formed by bundling a plurality of fibers. The fiber yarn bundle 20 is one of polyacrylonitrile (PAN) fiber, pitch fiber, and another organic fiber.

Microwave treatment step (S02): The fiber yarn bundle 20 is exposed to microwave treatment conditions to form an oxide fiber yarn bundle 20A. Microwave processing conditions include: a microwave frequency of 300 MHz to 300,000 MHz; Microwave power is 1 kW/m ² to 1000 kW/m ² ; Operating temperature is 100 ℃ to 600 ℃; Treatment time ranged from 1 minute to 40 minutes; The gas atmosphere is at least one of oxygen, air and ozone.

In addition, the method for manufacturing an oxidized fiber of the present invention is implemented in an embodiment in which a gas supply unit 42 for injecting a gas atmosphere into the oven body 33 is installed in the microwave processing unit 40, where the gas supply unit 42 The gas atmosphere injected into the oven body 33 by is at least one of oxygen, air, and ozone.

In addition, in the method for manufacturing an oxidized fiber, a supply unit 31, a winding unit 32, and an oven body 33 are installed in the transmission unit 30, the magnetron 41 and the gas supply unit ( 42) is installed, the supply unit 31 is used to provide a bundle of fiber yarns 2, a bundle of fiber yarns 20 can pass through the oven body 33, and the winding unit 32 is a fiber yarn Used to drag the bundle 20 for continuous transmission, the magnetron 41 is placed in the oven body 33 to generate microwaves, and the gas supply unit 42 has oxygen in the oven body 33 It is used to inject gas, and the winding unit 32, the magnetron 41, and the gas supply unit 42 are electrically connected to the control unit 50. The operations of the winding unit 32, the magnetron 41 and the gas supply unit 42 are controlled by the control unit 50, the spinning speed of the winding unit 32, the power and gas of the magnetron 41 The parameters related to the flux of the supply unit 42 are determined according to the properties or product specifications of the treated fiber yarn bundle 20.

In the manufacturing method of the oxidized fiber, the supply unit 31, the winding unit 32, the U.S. oven body 33 are installed in the transfer unit 30, and the supply unit 31 is used to provide a bundle of fiber yarns 2 Being, the fiber yarn bundle 20 can pass through the oven body 33, the winding unit 32 is used to drag the fiber yarn bundle 20 for continuous transmission, and the transmission unit as shown in FIG. At 30, an insulating unit 34 is installed inside the oven body 33. The heat storage effect of the heat keeping unit 34 can be utilized so that the interior of the oven body 33 can be maintained at a predetermined operating temperature to achieve the purpose of power saving. In FIG. 10, the supply unit 31 provides a bundle of fiber yarns 20 arranged in parallel to the oven body 33.

When the method for manufacturing an oxidized fiber of the present invention is performed, each of the insulating units 34 in the transmission unit 30 as shown in FIG. 3 is connected to the oven body 33 with respect to the transmission path of the fiber yarn bundle 20. Disposed on the upper and lower sides of the interior; Or alternatively, as shown in FIG. 10, the insulating unit 34 is disposed inside the oven body 33 to cover the transmission path of the fiber yarn bundle 20, so that the fiber yarn bundle 20 is uniformly Is heated.

According to a possible embodiment associated with the production of an oxidized fiber of the present invention, the insulating unit 34 can be selected from at least one of metal oxides, carbides and high microwave sensitive materials.

When the oxidized fiber production of the present invention is implemented, as shown in Fig. 3, the magnetrons 41 are disposed on the upper and lower sides of the transmission path of the fiber yarn bundle 20, respectively; Or alternatively, the magnetron 41 is arranged to cover the transmission path of the fiber yarn bundle 20, so that the microwave focusing process is performed uniformly on the fiber yarn bundle 20.

Referring again to FIG. 4, after a 12-kW/m ² microwave power focusing process at 220° C. was applied to the fiber yarn bundle 20 for 40 minutes, the oxidation degree of the oxidized fiber 21 was 89. % Is reached. However, after applying the normal heating process at 270° C. to the fiber yarn bundle 20 for 40 minutes without going through the microwave process, the oxidation degree of the oxidized fiber 21 reaches 70%. Therefore, the production of the oxidized fiber of the present invention can obtain a high degree of oxidation at a low temperature compared to a conventional heating process, thereby preventing thermal waste.

Referring to Table 3, Table 3 is a comparison table showing measured tensile strength of the fiber yarn bundle 20, the oxidized fiber yarn bundle 20A, and the carbon fiber yarn bundle formed by the following carbonization, where several sets of fibers The yarn bundle 20, the oxidized fiber yarn bundle 20A, and the carbon fiber yarn bundle are each treated by the prior art heating tube heating process and the microwave process of the method for producing the oxidized fiber of the present invention. With regard to the conventional heat transfer tube heating process, the treatment conditions are oven body temperature 270° C., treatment time 40 minutes, and the resulting physical properties are referred to as “Comparative Example 1”. In the microwave process herein, the treatment conditions are oven body temperature 220° C., microwave frequency 2450 MHz, treatment time 10 minutes, and obtains associated with microwave power of 24 kW/m 2, 22 kW/m 2, 16 kW/m 2, and 15 kW/m 2 The resulting physical properties are referred to as "Example 1", "Example 2", "Example 3", "Example 4", and "Example 5". In both Comparative Examples 1 and 1-5, the fiber yarn bundle 20 is made of polyacrylonitrile. In addition, a cross section of the oxidized fiber 21 of the bundle of oxidized fiber yarns 20A related to Comparative Example 1 and Examples 1 to 5 was taken with a scanning electron microscope to obtain a substantial sectional image, and oxidized to the sectional area of the oxide layer 211 Table 3 also shows the value obtained by dividing each of the cross-sectional areas of the fibers 21, that is, the proportion of the oxide layer 211 occupying the oxide fibers 21.

number Tensile strength of fiber yarn bundle (MPa) Microwave power (kW/m ² ) X ^*( MPa) Tensile strength ratio R* Comparative Example 1 865 0 2824 One 40% Example 1 865 24 3675 1.30 99.0% Example 2 865 22 3580 1.27 91.3% Example 3 865 20 3486 1.23 82.7% Example 4 865 16 3298 1.17 61.5% Example 5 865 15 3204 1.13 51.2%

X ^* : Tensile strength of carbon fiber yarn bundle

R ^* : Cross-sectional area of oxide layer divided by cross-sectional area of oxidized fiber

In Table 3, Example 5 shows that the tensile strength of the final carbon fiber yarn bundle by the bundle of oxidized fiber yarns treated by the microwave process of the present invention is 1.13 times that of Comparative Example 1, which improves the tensile strength by 13%. it means. In Example 5, the cross-sectional area of the oxide layer 211 divided by the value of the cross-sectional area of the oxide fiber 21 is 51.2%, that is, the oxide layer 211 occupies 51.2% of the oxide fiber 21. Example 4 shows that the tensile strength of the final carbon fiber yarn bundle carbonized by the bundle of oxidized fiber yarns treated by the microwave process of the present invention is 1.17 times that of Comparative Example 1, which means that the tensile strength is improved by 17%. . In Example 4, the cross-sectional area of the oxide layer 211 is divided by 61.5%, that is, the oxide layer 211 occupies 61.5% of the oxide fiber 21. Example 3 shows that the tensile strength of the final carbon fiber yarn bundle carbonized by the bundle of oxidized fiber yarns treated by the microwave process of the present invention is 1.23 times that of Comparative Example 1, which means that the tensile strength is improved by 23%. . In Example 3, the cross-sectional area of the oxide layer 211 is divided by 82.7%, that is, the oxide layer 211 occupies 82.7% of the oxide fiber 21. Example 2 shows that the tensile strength of the final carbon fiber yarn bundle carbonized by the bundle of oxidized fiber yarns treated by the microwave process of the present invention is 1.27 times that of Comparative Example 1, which means that the tensile strength is improved by 27%. . In Example 2, the cross-sectional area of the oxide layer 211 is divided by 91.3%, that is, the oxide layer 211 occupies 91.3% of the oxide fiber 21. Example 1 shows that the tensile strength of the final carbon fiber yarn bundle carbonized by the bundle of oxidized fiber yarns treated by the microwave process of the present invention is 1.3 times that of Comparative Example 1, which means that the tensile strength is improved by 30%. . In Example 1, the cross-sectional area of the oxide layer 211 is divided by 99.0%, that is, the oxide layer 211 occupies 99.0% of the oxide fiber 21.

Accordingly, the present invention further discloses an oxidized fiber 21, the oxidized fiber 21 includes an oxide layer 211 and a core portion 212, where the oxide layer 211 is external to the core portion 212. The oxide layer 211 occupies 50% or more of the oxidized fiber 21, or the cross-sectional area of the oxide layer 211 occupies 50% or more of the cross-sectional area of the oxidized fiber 21. As shown in FIG. 11, the oxide layer 211 occupies 80% or more of the oxidized fiber 21, or the sectional area of the oxide layer 211 occupies 80% or more of the sectional area of the oxidized fiber 21.

Of course, the oxidized fiber 21 of the present invention can be formed by processing the bundle of fiber yarns 20 using one of the methods for producing the oxidized fiber. Since the oxide fiber 21 of the present invention is formed under microwave processing conditions, the oxide layer 211 is a microwave oxide layer, and the oxide layer 211 of the oxide fiber 21 in the oxide fiber yarn bunch 20A is the oxide fiber 21 Occupy at least 50% of the

When the present invention is implemented, the fiber yarn bundle 20 can be one of polyacrylonitrile, pitch and other organic fibers. Of course, after obtaining the oxidized fiber by applying a microwave focusing process of 24 kW/m 2 to the fiber yarn bundle 20 for 10 minutes, the oxide layer 211 occupies 99.0% of the oxidized fiber 21, or The cross-sectional area of 211 occupies 99.0% of the cross-sectional area of the oxidized fiber 21.

Compared to the prior art, the method for producing an oxidized fiber disclosed in the present invention focuses microwaves using a microwave processing unit to apply an ultra-high-speed pre-oxidation process to a bundle of fiber yarns to process the bundle of fibers to form oxidized fibers. Thus, not only the oxidation time of the oxidized fiber is reduced, but the oxide layer in the oxidized fiber processed by the microwave and oxidation process occupies more than 50% of the cross-sectional area of the oxidized fiber, effectively reducing the shell-core structure of the oxidized fiber. Even there is no distinct shell-core structure in the oxidized fiber. Thus, a relatively positive and reliable means for improving the performance of the carbon fiber is provided.

The foregoing description merely represents exemplary embodiments of the invention, and is not intended to limit the scope of the invention. Accordingly, various equivalent changes, alternatives, or modifications based on the claims of this specification are all considered to be included in the scope of the present invention.

Claims (16)

A method of making an oxidized fiber used to pre-oxidize a fiber yarn bunch to form an oxidized fiber yarn bundle, wherein the fiber yarn bundle is formed by only one fiber, or alternatively, the fiber yarn bundle is Formed by joining a plurality of fibers; The bundle of oxidized fiber yarns is formed by only one oxidized fiber, or alternatively, the oxidized fiber yarn bundle is formed by joining a plurality of oxidized fibers; The method of manufacturing the oxidized fiber is:
Providing a bundle of yarns: preparing the bundle of fiber yarns; And
Microwave treatment step: forming the bundle of oxidized fiber yarns by exposing the fiber yarn bundles to microwave treatment conditions
A method of manufacturing an oxide fiber comprising a. The method according to claim 1, The microwave processing conditions are: 300MHz to 300,000MHz microwave frequency; Microwave power from 1 kW/m ² to 1000 kW/m ² ; An operating temperature of 100°C to 600°C; Treatment time from 1 minute to 40 minutes; And a gas atmosphere that is at least one of oxygen, air, and ozone. The method according to claim 2, The microwave power is 10 kW / m ² to 24 kW / m ² , Oxide fiber manufacturing method. The method of claim 2, wherein the microwave frequency is 2000 MHz to 3000 MHz, the operating temperature is 150°C to 350°C, and the treatment time is 5 minutes to 20 minutes. The method according to claim 1, wherein the bundle of fiber yarns is one of polyacrylonitrile (PAN) fibers and pitch fibers, an oxidized fiber manufacturing method. A method of making an oxidized fiber used to pre-oxidize a bundle of fiber yarns to form a bundle of oxidized fiber yarns; The fiber yarn bundle is formed by only one fiber, or alternatively, the fiber yarn bundle is formed by joining a plurality of fibers; The bundle of oxidized fiber yarns is formed by only one oxidized fiber, or alternatively, the oxidized fiber yarn bundle is formed by combining a plurality of oxidized fibers; The method of manufacturing the oxidized fiber is:
a. Providing a transmission unit and a microwave processing unit;
b. Providing the bundle of fiber yarns, placing the bundle of fiber yarns in the transmission unit, and moving the bundle of fibers to pass through the microwave processing unit;
c. Activating the microwave processing unit to generate microwave processing conditions by the microwave processing unit; And
d. Activating the transfer unit and moving the bundle of fiber yarns to be processed for a treatment time under the microwave treatment conditions by the transfer unit, so that the bundle of fiber yarns forms the bundle of oxidized fiber yarns.
A method of manufacturing an oxide fiber comprising a. The method according to claim 6, wherein the microwave processing conditions are: 300MHz to 300,000MHz microwave frequency; Microwave power from 1 kW/m ² to 1000 kW/m ² ; An operating temperature of 100°C to 600°C; And a gas atmosphere that is at least one of oxygen, air, and ozone. The method of claim 7, wherein the treatment time is 1 minute to 40 minutes. The method according to claim 7, The microwave power is 10 kW / m ² to 24 kW / m ² , Oxide fiber manufacturing method. The method of claim 7, wherein the microwave frequency is 2000MHz to 3000MHz, and the operating temperature is 150°C to 350°C. The method of claim 6, wherein the bundle of fiber yarns is one of polyacrylonitrile (PAN) fiber and pitch fiber. The method according to claim 6, The transmission unit is provided with a supply unit for providing the bundle of fiber yarns, a winding unit for continuously pulling and transmitting the bundle of fiber yarns, and an oven body through which the bundle of fiber yarns passes; In the microwave processing unit, a magnetron for generating microwave frequency and microwave power is installed in the oven body, and a gas supply unit for injecting a gas atmosphere into the oven body is installed. The method according to claim 12, wherein the winding unit, the magnetron and the gas supply unit are electrically connected to a control unit. The method according to claim 12, The inside of the oven body is provided with a thermal insulation unit (thermos unit), a method for producing oxide fiber. 15. The method of claim 14, wherein the insulating unit is at least one of metal oxide, carbide, and high microwave sensitive material. The method according to claim 12, wherein the arranged bundles of fiber yarns are arranged in the oven body in a repeating and winding manner and continuously irradiated by the microwave processing unit.

Images